UNIVERSITY  OF   CALIFORNIA 

COLLEGE    OF  AGRICULTURE 

BERKELEY 


Agricultural  Experiment  Station 

BENJ.    IDE    WHEELER,    President 
THOMAS    FORSYTH     HUNT,    DEAN   AND   DIRECTOR 
H.    E.    VAN    NORMAN,    VlCE-Dl  R  ECTOR    AND    DEAN 
University    Farm    School 


CIRCULAR  No.  127 
March,  1915 

HOUSE  FUMIGATION 

BY 
C.  W.  WOODWORTH 


California  is  remarkably  free  from  the  otherwise  ubiquitous  bedbug 
and  when  it  does  make  its  appearance  in  a  house  it  therefore  causes 
great  alarm.  It  is  most  frequent  perhaps  in  bunk  houses  and  is  one 
of  the  problems  of  everyone  employing'  migratory  laborers.  Very 
rarely  in  this  country  the  insect  is  found  in  poultry  houses. 


Proboscis 


Prdthorax 

Scutellum 
Elytron 


Micrograph  of  common  bedbug,  crushed  in  mounting  to  show  the 
mouth  parts  and  the  segments  of  abdomen,  and  sketch  with  these  joints 
in  normal  position  and  the  names  of  structures  used  to  distinguish 
species  of  bedbug.* 


*  The  only  household  species  in  California  is  the  common  bedbug  of  Europe, 
Cimex  lectularius  Linneaus,  probably  introduced  into  this  country  with  the 
earliest  settlers.  Another  bedbug,  Cimex  hemipterus  Fabricus,  is  a  tropical 
American  species  without  the  conspicuous  broad  flattened  edges  on  the  pro- 
notum.  Two  South  American  species  were  described  fifty  and  sixty  years  ago — 
Cimex  foedus  Stal,  similar  to  C.  hemipterus  and  Cimex  valdivianus  Philippi  close 
to  C.  lectularius.  Since  the  beginning  of  this  century  three  other  American 
species  have  been  discovered:  Haematosiphon  inodorus  Duges,  infesting  poultry 
in  Texas,  New  Mexico  and  southward,  having  a  proboscis  long  enough  to  reach 
back  to  the  base  of  the  hind  legs;  Cimex  pilosellus  Howarth  on  bats  here  in 
California  and  elsewhere  in  North  America  with  the  inner  edges  of  the  elytra 
longer  than  the  scutellum,  and  Oeciacus  vicarius  Howarth  in  nests  of  swallows 
from  California  and  elsewhere,  which  has  the  body  clothed  with  long  silky  hair. 


The  most  satisfactory  treatment  for  bedbugs  is  fumigation  with 
cyanide.  This  method  has  been  practiced  many  years  in  California, 
particularly  in  the  southern  part  of  the  State,  where  there  are  many 
people  familiar  with  the  treatment  of  orchard  trees  with  the  gas.  There 
is  no  reason  why  the  method  should  not  be  used  everywhere,  whenever 
the  bugs  appear  since  the  method  is  simple  and  easy  to  apply. 


MATERIALS  FOR  FUMIGATION 

Cyanide,  the  source  of  the  hydrocyanic-acid  gas,  should  be  pur- 
chased in  the  egg  form,  the  same  as  is  now  used  in  orchard  fumigation. 
This  is  a  pure  sodium  cyanide  and  each  egg  weighs  approximately  one 
ounce.  It  is  possible  to  obtain  good  results  with  other  forms  of  this 
cyanide  but  the  egg  form  is  most  convenient.  The  least  desirable 
form  is  powdered  cyanide,  because  of  the  violent  production  of  the 
gas  causing  spattering  of  the  acid  about  the  room. 

Acid  is  necessary  to  set  free  the  gas  from  the  cyanide.  Sulphuric 
acid  is  the  cheapest  acid  and  the  one  universally  used — it  is  the  prac- 
tice to  use  more  than  is  really  necessary  because  it  is  so  cheap.  The 
ordinary  strong  acid  is  the  proper  material  to  buy.  By  weight  use 
about  twice  as  much  acid  as  of  the  cyanide.  It  will  be  easier  to  measure 
out  the  acid  by  volume  in  which  case  one  and  one-quarter  parts  are 
about  equivalent  to  two  parts  by  weight. 

Water  is  necessary  for  the  proper  generation  of  the  gas,  so  that  the 
residue  sodium  or  potassium  sulphate  will  remain  in  solution  and  not 
crystallize.  The  amount  to  use  varies  with  the  character  of  the  cyanide. 
If  the  eggs  are  used,  twice  as  much  water  as  cyanide  is  necessary,  and 
if  lower  grade  material  is  employed,  use  three  times  as  much  water. 

The  recommendation  made  above  is  as  follows. 

By  weight  By  volume 

Cyanide    (eggs)         1  part 

Sulphuric  acid  2  parts  lx/4  parts 

Water  2  parts  2       parts 

THE  AMOUNT  TO  USE 

Measure  the  room  to  be  fumigated,  calculate  the  cubic  contents  and 
divide  the  number  of  cubic  feet  by  the  grade  of  cyanide  used.  Thus 
if  the  room  were  12  X  15  X  10  the  cubic  contents  would  be  1800,  and 
if  one  could  only  obtain  30  per  cent  potassium  cyanide,  60  ounces  would 
be  necessary.  If  98  per  cent  potassium  cyanide  were  available,  18 
ounces  would  be  enough  and  with  the  eggs,  which  are  equivalent  to 


128  per  cent  and  are  generally  so  labeled,  14  ounces  would  be  about 
right.  In  other  words,  when  the  cyanide  eggs  are  used  as  recommended 
use  one-quarter  less  ounces  than  the  number  of  hundreds  of  cubic 
feet  in  the  room. 

This  is  on  the  assumption  that  the  room  is  tight  or  made  so.  When 
the  construction  is  such  that  the  room  cannot  be  made  tight  good 
results  may  still  often  be  secured  by  making  the  dose  much  stronger. 
No  rule  can  be  given  for  dosage  under  these  conditions  and  the  fumi- 
gator  will  have  to  use  his  best  judgment  and  then  take  chances. 


HOW    TO    MAKE    THE    ROOM    TIGHT 

In  most  cases  it  will  pay  to  go  to  some  trouble  to  close  the  cracks 
about  windows,  chimney  holes,  etc.  This  can  be  done  by  pasting  paper 
over  them.  Simply  stuffing  paper  into  them  is  better  than  nothing. 
Professor  Herriek,  of  Cornell  University,  has  used  paper  simply  wetted 
with  water  instead  of  paste  and  found  it  would  stay  in  place  long 
enough  for  the  treatment.  A  great  deal  of  the  fumigation  in  this 
state  has  been  done  without  trying  to  make  the  room  tighter  than  it 
was  built,  arguing  that  it  was  cheaper  to  use  more  chemicals  than  to 
spend  the  time  making  the  room  tight.  This  will  have  to  remain  a 
question  for  the  judgment  of  the  fumigator.  As  remarked  above, 
rules  as  to  dose  can  onlv  be  given  on  the  basis  of  a  tight  room. 


APPARATUS  FOR  FUMIGATING 

Where  orchard  fumigation  is  practiced  and  regular  generators 
are  available  they  are  perhaps  the  most  satisfactory.  However,  any 
tight  wood  or  earthenware  vessel  of  proper  size  will  do.  We  have 
used  the  ordinary  wooden  water  bucket  and  the  common  bedroom  bowl 
and  pitcher,  also  crocks  and  jars.  It  is  better  to  have  several  generators 
when  the  room  is  large,  putting  not  over  a  pound  of  cyanide  in  each. 
Spattering  of  the  acid  out  of  the  generator  is  less  liable  to  occur  when 
the  amount  generated  is  small.  We  have  followed  the  practice  of 
spreading  out  several  layers  of  newspaper  upon  which  the  generator 
is  set  to  make  sure  not  to  spatter  the  floor.  A  paper  sack  to  hold  the 
cyanide  for  each  generator  is  recommended  to  give  ample  time  to 
get  out  of  the  room  before  the  production  of  the  gas  begins,  since  the 
acid  requires  some  time  to  soak  through  the  paper  and  attack  the 
cvanide. 


TIME    OF    TREATMENT 

The  practice  in  orchard  fumigation  is  to  leave  the  tents  on  the  trees 
fifty  minutes  or  an  hour,  and  at  least  this  length  of  time  should  be 
allowed  in  house  fumigation.  Our  practice  has  been  three  or  four 
hours.  For  instance,  if  a  house  is  vacated  from  ten  to  three  o'clock 
the  fumigation  could  take  four  hours,  leaving  an  hour  for  ventilation, 
which  is  ample.  In  empty  houses  the  commoner  practice  is  to  fumigate 
in  the  afternoon  and  leave  them  closed  until  the  following-  morning. 


DISPOSAL   OF  REFUSE 

The  residue  from  fumigation  generators  is  sodium  or  potassium 
sulphate  dissolved  in  a  liquid  which  contains  an  excess  of  sulphuric 
acid  and  more  or  less  hydrocyanic  acid.  This  may  be  disposed  of  by 
digging  a  small  hole  in  the  ground  into  which  the  generators  are 
emptied  and  the  hole  then  filled  up  with  soil.  The  material  will  tem- 
porarily injure  the  soil,  but  not  permanently. 

The  vessels  need  only  be  washed  out  with  water.  Sometimes  in  a 
wooden  or  porous  earthenware  vessel  an  effervescence  may  appear  some 
days  later.    This  is  the  sulphate  and  is  perfectly  harmless. 


PRECAUTIONS 

The  most  important  precaution  is  to  avoid  breathing  the  strong 
gas  as  it  comes  from  the  generator.  Strong  cyanide  gas  is  instantly 
fatal  and  breathing  it  would  be  equivalent  to  looking  down  the  muzzle 
of  a  gun  to  see  the  bullet  start.  If  this  one  fact  is  kept  clearly  in  mind 
fumigation  is  not  more  risky  than  handling  firearms. 

After  fumigation  is  over  it  is  quite  safe  to  enter  a  room  and  open 
the  windows,  but  it  is  wise  not  to  breathe  the  air  any  more  than 
necessary  in  doing  so. 

When  fumigation  is  being  done  it  is  well  to  vacate  the  whole  house 
so  as  not  to  take  any  chances. 

Cyanide  gas  does  not  injure  any  fabric  nor  metal,  but  would  kill 
plants  at  the  strength  used  for  house  fumigation,  and  all  moist  food 
should  be  removed  because  the  gas  is  absorbed  by  water. 


